Blow-molded double-walled resin bodies and lids can serve as insulated containers when filled with an insulation material. A hinge between the body and lid allows the lid to pivot open for access to the interior of the container, and at least parts of the hinge are preferably formed in the blow molding process that creates the body and lid.
After a blow-molded double-walled body and lid are filled with insulation material, the lid becomes heavier, which requires that the hinge supporting the lid for pivotal motion relative to the body be made robust and durable so as not to fail during the life of the product. Hinges for such blow-molded, insulated containers must also meet many other requirements, including low cost of manufacture, ease of assembly, reliable operation, and resistance to customer abuse.
Hinges have been formed in blow-molded double-walled containers by boring recess holes in either the body or lid so that projections mating with the holes can be snap fit into place. For several reasons, this is unacceptable for a container that will be filled with a fire-resistant insulation material. Such insulation is preferably pourable into the interwall spaces of the container and lid and later sets to a solid state. Hinge projections cannot simply extend through recess holes into interwall spaces of a double-walled container, because they would not be able to pivot after an insulation material becomes solid. Inserts must be arranged in the bore holes to receive the projections and separate the projections from any bond with the insulation material, but this requires extra parts that must be positioned to complete hinge assembly.
Another serious problem is that any holes bored into interwall spaces to accommodate hinge projections allow insulation material to leak out around the inserts at the edges of the holes when the insulation material is freshly poured and still flowable. Leaks around the hinge holes spoil the appearance of the container and require either an expensive cleanup or scrapping of a product.
We have devised a hinge that meets the requirements of low cost, reliability, and durability without requiring bore holes in a hinge region. Our hinge and its assembly aim at all the desired advantages implemented in a configuration that gives a container an attractive appearance.